The anglerfish gets its name from its unique evolutionary adaptation for hunting, a front dorsal fin known as an irisium that acts as a lure. To humans, Illithium may resemble a fishing rod, but to potential prey, it resembles an aquatic insect. For example, the frogfish subgroup of anglerfish camouflages itself by raising and lowering its front fins to attract its next prey. When close enough, the frogfish stops moving its fins and swallows the target.
Marine biologists have long wondered about the identity and precise location of the neurons that control important motor functions in the dorsal fin. Thanks to recent research at Japan’s Nagoya University, this mystery appears to have been solved, and it may help us better understand the evolutionary history of vertebrates.
To identify and catalog the frogfish’s motor neurons, a team led by bioagriculture professor Naoyuki Yamamoto first injected tracers into the frogfish’s spinal cord, specifically the ventral horn, which controls and coordinates swimming movements. Once in place, researchers were able to visualize and observe which motor neurons lit up during activities such as raising and lowering the ilium to attract prey. They then performed a similar tracer injection experiment on the white rockfish to compare neurological activity between the two species. The result is Journal of Comparative Neurologysurprised them.
“This is an extremely rare case,” Yamamoto said in a statement.
The researchers discovered that the motor neurons responsible for the frogfish’s iliac bones are located in the upper back, also known as the dorsal zone. Interestingly, however, these neurons are completely separate from the neurons that issue commands to the fish’s other three dorsal fins, which are located on the underside of the ventral horn, called the ventral zone. In contrast, all dorsal fin motor neurons of the filefish are present only in the ventrolateral region.
“Their location has moved [during evolution] Yamamoto added that the “unprecedented” discovery could have implications far beyond frogfish.
“As land animals, we do not have fins, but considering the distribution in the ventral horn of the spinal cord, our forelimbs and hindlimbs resemble pectoral and pelvic fins, and our ancestors once had dorsal fins. ” he said. We explain that the group organization of motor neurons is similar across vertebrates. Therefore, unique neuronal arrangements may exist in some other species that exhibit specialized behaviors.
“Our study provides a new perspective on motor neurons, and we hope it will encourage similar studies in other species and help scientists understand the rules that govern their organization. ” said Professor Yamamoto.
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